The Amazon river dolphin is the largest and the most well known species of river dolphin. It is known by the scientific name Inia geoffrensis and has three subspecies. It has long beak and streamlined body to adapt to the environments. It lacks hairs on the body like other dolphins, but it has melon for echolocation and is able to move its neck about 180 degrees. The most dominant characteristic is its body color. It depends on each dolphin, but usually it is tinged with pink and sometimes bluish gray or off-white. Uniquely, the male and the female dolphin segregate from each other and come out to the main river to meet during the mating season. For habitat, it can live any fresh water and the dominantly observed at the Amazon and Orinoco watersheds. It lives on crustaceans, crabs, turtles, and 50 kinds of fish. It prefers to be alone, not in groups. However, sometimes a flock of Pink dolphins can be seen, but it might be scattered immediately.

There are many myths about the Pink dolphin that it transforms into human at night and attracts the people. The natives of the Amazon river has believed Boto as a sacred creature and treat it carefully. Despite of the beliefs among the natives, the number of the Amazon river dolphin has decreased by habitat degeneration, overfishing, deliberate killing, and pollution. The International Union for the Conservation of Nature and Natural Resources has determined it as Vulnerable and tried to prevent extinction.

Contents

Taxonomy

In Inia geoffrensis species, there are 3 subspecies. According to some old information or classifications, I. g. boliviensis has been classified to different species, but by IUCN (International Union for the Conservation of Nature and Natural Resources) now put it inside the Inia geoffrensis species.

Anatomy

The Amazon River Dolphin has a medium sized, stocky body with a long beak. The body is streamlined form that allows to swim effectively with less water resistance. It can weigh up to 300 pounds and, usually the male dolphin is 8 inches long while female is 1.8 inches. It has a prominent forehead and there are no hairs on the other parts of body except stiff hairs on the beak. The hairs are sensory organs for the dolphin and they helps to perceive or sense the prey. It has uniquely a dorsal ridge, but does not have a dorsal fin. Its tail fin, called the fluke and flipper, are large enough to maneuver in the river waters during river floods. The pectoral fin and the tail help to control its movement.

Forehead
The Amazon Dolphin has tiny, little eyes with acute eyesight. The well-developed eyes allow it to see in detail both in the water and on the shore. It also has two small ears on their head. Inside its long beak, there are 24-34 conical and molar-like teeth. In the front of the mouth, the conical teeth are used for holding prey, and the molars help to grind food in the back. Its teeth can detect the sound and the prey's location like antenna. [2] The another unusaul characteristic in the Amazon River Dolphin is that it can move its neck quite freely, turing the head 180 degrees. [3] It makes the dolphin to look down or to the sides.[4] There is an organ called melon on the head also. It is a fatty organ used for echolocation. [5]

The body color
The most unique feature of the Amazon River Dolphin is its color. It is also commonly known as a "pink dolphin", because some of the dolphins are pink. However, not every dolphin is pink. There are variations that it can be light gray, pink, brown, or mixed with these colors. The color on their body depends on the age of the dolphin that the older it is, the lighter the skin becomes. Also the sun's ray can impact its color that it cause to decrease pink pigmentation. It is much possible that the dolphins live in dark water contain more pink color than those live in light environment. They even blush into pink, when they are excited. [6][7]

Brain & Sensory organs
The dolphin's brain has complex structure that can contain 40% more capacity than human beings. [8] The brain is posterior to the traches.

An olfactory nerve and lobes, which is sense of smell, lack in dolphins. They are thought not to have ability to smell, but they have a sense of taste.

Reproduction

The female dolphins like to hide themselves from unprotected areas, while the males prefer to be in the main rivers. This preference makes the separation. In cetaceans, it is very uncommon that males and females have segregation before mating. During the mating season, all dolphins go to the rivers at the low water obligatorily to find the spouse and mate. [9] The reproduction is year-round for the botos and they have 10-11 months for gestation. There are various factors influenced that influence reproduction seasonally.

Ecology

Amazon River Dolphin range

Rivers and lakes in Amazon and Orinoco drainage basins

The place where the Amazon river dolphin lives in is Amazon and Orinoco watersheds, as it shows in the name. Actually it can live in any fresh waters except the saline waters, estuaries, strong rapids and waterfalls. [11] Although the dolphin can be observed in other places, it seems like it prefers the deep waters. However, the big changes of water levels influences the popularity of the botos in that region. With the large amount of waters by floods or inundation of water, the dolphins comes out to the river and enjoys swimming. Confluences, sandbars, and sharp bends are also its favorite habitat. During the high season, it swims between the trees.
Using the front teeth, it catches prey to eat, and crustaceans, crabs, turtles, and some kinds of fish are food for the dolphin. It eats almost 50 species of fish. Its speed is usually 2.4 to 5.1 km/h and it can be increased also. [12]The dolphins gather in the feeding area and the group of the dolphins babely can be seen. The Amazon river dolphins usually do not form the family group and flock, but they just swim only by itself. The closest relationship in botos is mother and the her child. Sometimes the dolphins make a group of two or a little more, but immediately goes away from each other, finding another temporary friend. Although it is true the pink dolphin is associated with other dolphins, it prefers to be alone and be observed by itself more frequently. [13]However, Botos are unique animals now that the process to extinct happens to them. The dolphin's distribution along the river has been changed because of pollution, development by humans, and fisheries. [14]The Amazon River dolphin is protected by the International Union for the Conservation of Nature and Natural Resources (IUCN). There has been little increase on numbers of boats, but still it need special protection, not being threatened by artificial pollutant. [15]

Mythology

The Amazon river dolphin has been thought as a sacred animal within the natives of the Amazon. According to the Amazon River myth, it usually changes into the image of human. Some people insists that, when Boto becomes human, his genitals resemble those of a humans. [16]

One of them states that, at night the Boto transforms to a handsome, young man and fascinates the girls. When he attracts them, it is believed that he takes the girls to entranced underwater world, called Enkangji. Then he comes back to the Amazon river at morning, going back to the dolphin itself again.

Another myth say that a girl has gotten the love from the pink dolphin. There are stories of the girl who fell love with the dolphin and got pregnant, and the people who were attracted by the botos transformed into the beautiful women on canoes. Also, in some area, people believe killing the pink dolphin brings bad fortune to them. Moreover, if a person makes eye contact with the boto, the nightmare will occur to him since he has seen its eyes. Traditionally, boto has been considered as a guardian for the Amazon river. [17]

Various names

The Amazon river dolphins have various names because of its color or habitat. To make it clear, IUCN declared the names in the list down.

Therapy

Therapy for children with Pink Dolphin

Dolphins have been a method to treat the people with disabilities. From cancer to psychomotor faults, dolphins are believed and also it has proved that they alleviate the problems and illnesses. [19] For an instance, Ms. Deena Hoagland, LCSW, has found improvement on her son, when he was with the dolphin. Her son, Joe had had 3 open-heart surgery and his body was weak from a stroke, especially on his left side. However, Joe exercised, played and swam with the dolphins. Surprisingly, he got well both physically and psychologically. [20] Deena and her husband believed the dolphins have motivated their son in various ways, and they created Island Dolphin Care(IDC). As the dolphins are proved to be beneficial to people with disabilities, therapy with the pink dolphin has been created also. The Pink Dolphin's Therapy Center at the Ariau river was constructed on November 2008. The dolphins emit the ultrasonic waves that work to circulate in human's body and give advantages to the nervous system. Also, it is believed that the ultrasound alleviates the problems and figures out the location of problems inside the body. The dolphins emit the ultrasound naturally and it helps the cancer patients too. Another benefit from the dolphin therapy is that it motivates person emotionally and produce endorphins that help to improve the body functions. [21]Today, dolphin therapy has been recognized with its effect and improvement. There are many places that children can experience the therapy like in Brazil or Florida. Also, it brings lots of positive outcomes with people's problems.

Threats

The number of Amazon river dolphin has decreased and disappeared by several threats. Now it is protected by the International Union for the Conservation of Nature and Natural Resources (IUCN).

Habitat destruction

Building dams, hydroelectric improvement, deforestation and other development from human populations makes difficult environment to the botos. It is much more challenging for them to survive in the place where has been their own place. Expanding of human popularity leads mor lands and more foods to supply and satisfy them. By deforestation, the fish productivity has been short of supply, while humans still develops the plain land without thinking of the effects on the ecosystem. Moreover dams prevent migrations and bring artificial environment to not only dolphins but also other aquatic animals. With lower pH levels and fewer fish, the botos live hard to survive.

Overfishing

Overfishing is another factor of deduction of the dolphins. Fishery is all around the Amazon river and the dolphins are caught too much thoughtlessly. Not being satisfied with already sufficient amount of catch, people try to catch more and more as possible as they can.

Deliberate killing

Fishermen usually kill the fish on purpose to attract the Amazon river dolphin to catch. More fishermen catch the fish as bait, the less supply of foods the dolphins have.

Pollution

Pulp mills, and heavy metals pollute the Amazon river and also the environments around the river. Also, air pollution, and water pollution influence the decreasement of the pink dolphins. [22]